Film applicator



Feb, 1?, R948. J, BRADLEY, JR

FILM APPLICATOR Filed Aug. 15 1946 I N V EN TOR. BYJOHN uf'fim myvk A T'TORMEF Patented Feb. 17, 1948 FILM APPLICATOR John J. Bradley, Jr., Walpole, Mass., assignor to Boston Varnish Company, Everett, Mass., a corporation of Massachusetts Application August 15, 1946, Serial No. 690,785

2 Claims. (Cl. ill-62.5)

The present invention relates to a film spreading tool and more particularly to a film applicator suitable for hand operation for forming thin films of carefully controlled uniformity of thickness from plastic or semi-liquid materials, such as paints, varnishes, lacquers and the like.

In the coating composition manufacturing industry, it is common practice to test formulations of coating materials for various characteristicssuch as fastness to light, weather resistance, particle size of the color or pigment, etc., by making up test panels coated with thin films of the materials to be investigated. In order to secure comparable results in the testing of different coating compositions and also in order to determine particle size and uniformityof particle distribution, it is highly desirable that the test films be uniform in thickness within exceedingly close tolerance limits. It is also desirable that films formed from different compositions at the same or differentv times and films formed from a given composition at different times should be the same in thickness. This ideal has been exceedingly diflicult of attainment. ordinary procedures for applying paint, varnish and similar films are entirely inadequate. Films formed with a brush will vary greatly in thickness over their area, depending upon the skill of the operator. Also, it is impossible even for a skilled operator to lay films at different times which are the same in thickness even if the paints are identical in composition. The same difficulties are experienced with other procedures such as spraying, roll coating and the like.

The present invention has as an object to provide a hand tool of simple construction which will produce films of great uniformity in thickness even in the hands of a relatively unskilled operator. An additional object is to provide a tool of this character which may be manufactured to close tolerance limits at relatively low cost. Other objects of the invention will in part be obvious and will in part appear as the description proceeds.

In accordance with the invention the film spreading tool is formed from three principal parts. The film contacting and spreading part is provided by a central bar, which may be formed from round rod or bar metal stock, by forming thereon a series of fiats. The bar is provided at each end with means, having a plurality of flat faces, for properly positioning the bar with respect to the surface on which the film is to be spread during the spreading operation.

The invention will be better understood from The the following detailed description of a presently preferred embodiment, and from the accompanying drawing forming a part hereof, wherein Fig. 1 is a perspective view of the tool, illustrating the .manner in which it is operated;

Fig. 21s an elevation of the tool shown in Fig. 1; Fig. 3 is a mid-sectional view taken on a plane lying at right angles to the axis of the bar, and Fig. 4 is a fragmentary sectional view similar to Fig. 3 but drawn to an enlarged scale.

The film spreading tool comprises a central working portion or bar 2 and, at each end thereof, spacer blocks 4 and 6. The bar 2 is formed from round metal stock which is machined to provide an outer surface 3 which is cylindrical. Preferably the outer cylindrical surface 3 is finished by a grinding or polishing operation to that the cylindrical surface is smooth and true. The cylindrical surface 3 of the bar 2 is divided into segments by a series of flats, four in number, in the tool selected for purposes of illustration, and indicated at l0, l2, l4 and IS. The opposite fiat surfaces l0, l4 and I2, [6 are parallel to each other and to the axis of the surfaces 3 and are :paced the same distance from this axis. The fiat surfaces I0, I2, I 4 and I8 can be formed on the bar 2 by any suitable simple machining operation. Conveniently they may be formed by a surface grinding operation. These flats also are finished to provide a smooth and preferably a polished surface.

The bar 2 is provided with opposite end portions 18 and 20 of reduced diameter, as compared with the main body of the bar 2, for the reception of the end blocks 4 and 6. Conveniently the end portions I8 and 20 may be formed by a turning operation and then knurled and driven into the apertures 22, 24 in the end blocks 4 and'6 with a press fit.

The block 4 is provided on its periphery with a series of fiat faces 26, 28, 30 and 32 corresponding in number to the number of flat surfaces l0, I2, I4 and I6 for a purpose which will appear hereinafter. The block 6 is likewiseprovided with a series of fiat faces 34, 36 and 38 corresponding to the faces 26, 28 and 30 of the block 6 and a face (not shown) corresponding to the face 32. The blocks 4 and 6 are disposed on the bar 2 with their corresponding fiat faces lying in the same plane. Thus the faces 26, 34 lie in the same plane as do the pairs of faces 28 and 36, and 30 and 38.

The blocks 4 and 6 are arranged on the end portions l8 and 20, in the embodiment selected for purposes of illustration, so that the flat surfaces [0, i2, I4 and [8 are inclined to the adiacent faces on the blocks 4 and 6 at an angle of about 22 This angle may be varied in different tools between about-22% and 45, depending upon conditions such as the nature of the plastic material with which the tool is to be used. This angular relationship is shown to best advantage in Fig. 4, from which it will be observed that the flat i4 is inclined to the center line 42 of the bar. 2 at an angle of about 22 2 and consequently .is inclined at the same angle to the lower face 30 of the block 4. and the lower face 38 of the block 6. The lower edge of flat surface l4, indicated at 44 in Fig. 4, is thus offset horizontally from the center line 42. In the instance illustrated, this offset amounts to about a; of an inch.

The other flat surfaces III, 12 and IE, it will be understood, are similarly related to the center lines of the bar 2 and the other adjacent faces of the blocks 4 and 6.

' The corresponding pairs of faces on the blocks 4 and 6 are spaced at different distances from the axis of the cylindrical surface 3 of the bar 2 so that the various edges of the flat surfaces i0, l2, l4 and I6 which correspond to the edge 44 of fiat surface i4 will be spaced at different distances from the corresponding faces of the blocks 4 and 6. Referring to Fig. 4, the edge 44 of the flat i4 is spaced from the face 30 of block 4 (and face 38 of block about-0.0040 inch. Each segment of the cylindrical surface 3 is correspondingly spaced a different distance from its adjacent pair of faces on blocks 4 and 6. Thus each fiat segment of the cylindrical surface 3 may be employed to form a film of a different thickness from that which may be obtained with the other segments. Conveniently, the end face of one of the blocks 4 and 8, such as the face 46 of block 6, is provided with suitable indicia or legends 40 to indicate to an operator the thickness of film which will be formed when a particular pair of block faces is disposed on the surface to be coated.

The tool may be used to form film from various semi-liquid or plastic materials, such as paints, varnishes, enamels, lacquers and other coating materials referred to herein as plastic materials. The operation of the tool will best be understood from Figs. 1 and 4 in which a surface on which a film is to be spread is indicated at 50. A mass of a suitable size of the material to be spread, indicated at 52, is' first placed on the surface 50. The tool is then advanced against the mass 52 in the direction indicated by the arrow 54, in Fig. 4, that is with one of the segments of the cylindrical surface 3. of bar 2 disposed to engage the mass 52. As the tool is advanced, the mass 52 is thinned down and spread out as it passes under the lowermost cylindrical segmcnt of the bar 2. At the edge indicated at 44 in Fig. 4, the tool passes out of contact with the coating material, leaving a thin uniform film 53 on the surface 50. During this operation the surface l4, due to its inclination to the surface 50, and due to the relatively sharp edge provided at 44, serves to prevent adhesion of the plastic maformed has a thickness It will be observed that the manufacture of.

the tool involves only relatively simple machining operations which may be performed at little cost, but that nevertheless the shape and disposition of the various working surfaces of the tool may be controlled within close tolerance limits. The films formed with the tool show great uniformity of thickness throughout their area.

The foregoing description of one'particular film spreading tool embodying my invention is made by way of illustration and pot of limitation. It will be appreciated that variations in the methods by which the tool is made'and in the form and arrangement of the parts may be made by those skilled in the art without departure from the invention as expressed in the following claims.

Having thus fully described my invention, what I claim is:

i. A hand tool for forming films on flat surfaces from plastic materials which comprises a central bar having on its periphery alternate cylindrical and flat portions, a block secured at each end of said bar having fiat faces corresponding in number to the flat surfaces on said bar, the corresponding faces on the two blocks lying in the same plane and being spaced the same distance from the axis of the bar.

2. A hand tool for forming films on flat surfaces from plastic materials which comprises a central bar having on its periphery a plurality of coaxial cylindrical surfaces separated by intervening flat surfaces depressed below the cylindrical surfaces and lying parallel to the axis of said cylindrical surfaces, a block secured to each end of the bar and having a plurality of flat faces each disposed parallel to said axis and terial to the tool through surface tension effects.

I have observed that the film 54 which is adjacent to but spaced from a cylindrical surface, corresponding faces of the blocks lying in the same plane and being spaced the same distance from said axis, and different pairs of corresponding faces beingspaced different distances from said axis, each of said flat surfaces on the bar being inclined to the adjacent face of said blocks.

JOHN J. BRADLEY, Ja.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name I Date 2 151,183 Bradley et al Mar. 21, 1939 2,214,787 Dickhaut et al Sept. 17, 1940 2,301,619 Davis Nov. 10, 1942 FOREIGN PATENTS Number Country Date 18,27 Great Britain 1913 310,215 Great Britain-. Apr. 25, 1929 

